Not Applicable
Not Applicable
1. Field of the Invention
The field of the present invention is networks and internetworks. More particularly, the invention relates to address interworking between networks in an internetwork.
2. Description of the Prior Art
By way of background, the proliferation of different networking technologies has created an increasing need for internetworking. Schemes for internetworking are required to connect endpoints on different networks, or to use a different network for part of the path between two endpoints that use the same networking technology. For example, a telephone user may want to be connected to an Internet telephone user, or a call between two telephones may be routed via a packet-switched network, such as an IP or ATM network. Internetworking is handled by gateways (GWs) that connect to both of the networks being interconnected. There are many aspects to the internetworking problem. Primarily these consist of interworking the (a) user-plane protocols, (b) routing protocols, (c) signaling protocols, and (d) addressing schemes. It is with the problem of address interworking that the present invention is concerned.
Simply stated, the problem presented for solution is as follows: When a service request (packet or call) identifies a destination by its network address (say a network 1 address), how does a gateway to a second network, say network 2, through which this service is handled, determine the network 2 address of the egress gateway through which to reach the destination? As used herein, the term xe2x80x9ccallxe2x80x9d signifies a request for a circuit in a circuit-switched network, or a virtual circuit in a packet-switched connection-oriented network with or without additional feature processing.
Generally speaking prior art address internetworking solutions fall broadly into four categories: (i) schemes that send address resolution messages when a call/packet arrives (xe2x80x9cpullxe2x80x9d information), (ii) schemes in which address resolution information is sent in routing protocols (xe2x80x9cpushxe2x80x9d information), (iii) schemes that use administered address translation tables at gateways, and (iv) schemes that use encapsulated/mapped addresses with routing protocols spreading reachability information.
Internetworks that are of interest currently include PSTN (Public Switched Telephone Network)-ATM, IP-ATM, and PSTN-IP internetworks. Example scenarios include (i) A telephone-to-telephone call routed through an ATM network, (ii) An IP-endpoint-to-IP-endpoint flow routed through an intermediate ATM network, and (iii) A telephone-to-telephone call routed through an IP network. The PSTN uses 8-byte E.164 addresses, IP networks use 4-byte IPv4 addresses, and ATM networks use 20-byte ATM End System Addresses (AESAs).
Solutions proposed for the address interworking problem in these three internetwork combinations fall into the first three categories of address interworking solutions listed above. It is believed, however, that the fourth category of address interworking solution, which has been limited to IP-ether-net internetworking, may be used as a starting point for a comprehensive address interworking solution for use in PSTN-ATM, IP-ATM and PSTN-IP internetworking environments.
The foregoing problems are solved and an advance in the art is provided by a system that uses encapsulated/mapped addresses with routing protocol dissemination of reachability information in an internetwork that includes a first network using first network addressing communicating via one or more internetworking gateways with a second network using second network addressing. The gateways register one or more first network addresses in the second network as first network address-encapsulated or- mapped second network addresses. Reachability information regarding the first network address-encapsulated or -mapped second network addresses is then disseminated through the second network. When a communication request containing a first network destination address is received at one of the gateways, the receiving gateway performs encapsulation or mapping of the first network destination address into a first network-encapsulated or -mapped second network destination address. It then routes a communication request containing the first network-encapsulated or -mapped second network destination address through the second network based on the disseminated reachability information.
In preferred embodiments of the invention, plural ones of the first network address-encapsulated or -mapped second network addresses are reachable through a single one of said gateways. One or more of the first network address-encapsulated or -mapped second network addresses may also correspond to a range (summary) of first network addresses. Part of the first network address-encapsulated or -mapped second network addresses may contain high level protocol information that is propagated during the spreading of reachability information. High level protocol information may include terminal capabilities, feature information, or the like.
The first and second networks can be of various types. For example, the first network may be a PSTN and the second network may be an ATM network. In that case, the E.164 numbers used as addresses in the PSTN can be encapsulated in the AESAs used in the ATM network. The first network may also be an IP network with the second network being an ATM network. In that case, the IP addresses used in the IP network can be encapsulated in the AESAs used in the ATM network. The first network may likewise be a PSTN and the second network may be an IP network. In that case the E.164 numbers used as addresses in the PSTN may be mapped to the IP addresses used in the IP network.